Mousitsas, thank you very much for such comprehensive info! That's actually answering all my questions :)
I also found that KLX650R forks unlike C model have some adjustements but rest is totally same with C model, so perhaps I'll go for it...thou I can't really complain about 43 mm stock forks on SR43.

Now I am buried deep in making full-scale sump guard from what turned out to be (D'oh! How would I have known that this material is that) not aluminium but some hard aly alloy, so I am having bad time half-bending-half-bolting that thing (have no welder for aluminum) from 5 mm flat I bought by chance. It's so non-bendable, even heating it not helping. When done I probably will have pattern for folding it and process documented, but if all will work as I plan it's going to be killer strong sump guard...